Radioreceiver



Jan. 15, 1935. G. JoBsT E1' Al.

RADIORECEIVER Filed April 25, 1931 JI Il INVENTORS GNTHER JOBST BY WLDE Pi/HNERT ATTORNEY Patented Jan. 15, 1935 PATENT oFF'IcE n i 1,987,956U A LRADIORECEIVER G'nr'itherJobsti and WaldemarsWehnert, Berlin,

Germany,

assignors; to Telefunken Gesellschaft fiirl VDrahtlose Telegraphie m. ,b. H., Berlin,G ermany, acorporation of Germany Applicatipvn April 25,1931, seriall 1\m.,53.2,f792` 4Ir1'- GrerIna-xiyOctober-15,193() The present vinventonfrelates to'receivers,` and moreparticularly `toreceivers `utilir/Jin'g tubes supplied frcm direct current networks.

Gasflled external control type of tubes ofthe kind' disclosed in Patent No'. 1,889,749, issued December '6, 1932, exhibit thevpropertyzto suppress low frequencies during amplification, and they are therefore especially suited for the suppression ofthe disturbing humin alternating current receiver sets., The, chief aim in the use of alternating; currentreceiver sets is to suppress thehumming notecausedby the variation ofthe filament potential in respect of the middle of the transformer, that is to say, the grounded point of the tube itself.

It has been found that gas-filled external control type tubes are not only able, in connection with the use of direct current amplifiers, to eliminate the supply line hum which is due to a variation in the heating potential superposed upon the direct current potential, but that what is more important and valuable is that the entire fluctuations in potential disturbances due to commutators or rectifier equipment in respect of the grounded point of the apparatus may be obviated by virtue of the property of such tubes to suppress audio frequencies.

The point grounded in the apparatus in this instance need not be the middle of the lament of the audion, indeed, the latter may present a fall of potential amounting to several volts in respect of it. In this manner expensive smoothing means provided usually in direct current electric receiver sets designed for series heating, more particularly expensive choke-coils for the lament may be dispensed with. In fact it is feasible to get along with simple smoothing means for the audion and grid biasing potentials in the end or power tube. The use of external control tubes for the other stages namely, the radio and audio amplification stages is associated With the advantage that no grid biasing potentials at all are required, for these would in turn require smoothing means.

The novel features which we believe to be characteristic of our invention are set forth in particularity in the appended claims, the invention itself, however, as to both its organization and method of operation will best be understood by reference to the following description taken in connection with the drawing in which we have indicated diagrammatically one circuit arrangement whereby our invention may be carried into effect.

Referring to the drawing, Al denotes a gasiilled audion tube coupled with theantenna circuit, R is a Yregeneration control condenser, A2 ahigh vacuum external control type tube,gD an internal control power tube. R1 and R2 designate ycoupling resistances,'T is the telephoneI receiver and W the lament resistance, and E the ground connection. The plate and the grid leads contain smoothing impedances.

As shown in the schematic drawing, tube A1 may be a detector tube while tubes A2 and D may` 13e-arranged s0 as t0. formv an. audiofrequency amplifier.

While we have indicated and described one arrangement for carrying our invention into effect, it will be apparent to one skilled in the art that our invention is by no means limited to the particular organization shown and described, but that many modifications may be made without departing from the scope of our invention as set forth in the appended claims.

What we claim is:

l. ln a radio receiver including a detector and an audio frequency amplifier, said detector comprising an electronic tube provided with an anode, a cathode and an external control electrode, an atmosphere of gas within the tube the relation between the geometry of the tube and the gas pressure being such that radio frequencies are amplified more efnciently than audible frequencies, a cathode energizing circuit for said tube, a source of fluctuating uni-directional current having negative and positive terminals, means for connecting the anode of said tube to the positive terminal of said source, means including a resistance element for shunting the cathode energizing circuit across said two terminals and a capacity effectively shunted across the positive and negative terminals of said source for lessening the amplitude of hum frequencies passing through the cathode energizing circuit said hum frequencies being poorly amplified in the tube due to said relationship between the geometry of the tube and the gas pressure thereof.

2. In amplifying apparatus an electronic tube provided with an anode, a cathode and an external control electrode, an atmosphere of gas within the tube, the relationship between the geometry of the tube and the gas pressure being such that radio frequencies are amplified more eiiiciently than audible frequencies, a cathode energizing circuit for said tube, a source of uctuating uni-directional current having negative and positive terminals, means for connecting the anode of said tube to the positive terminal of said source, means including a resistance path for connecting the cathode across the source and a capacity effectively shunted across the positive and negative terminals of the source for lessening the amplitude of hum frequencies passing through the cathode energizing circuit, said hum frequencies being poorly amplified in the tube due to said relationship existing between the geometry of the tube and the gas pressure thereof.

3. In radio receiving apparatus a rst electronic tube provided with an anode, a cathode and an external control electrode, an atmosphere of gas within the tube, the relationship between the geometry of the tube and the gas pressure being such that radio frequencies are amplified more efliciently than audio frequencies, a tuned input circuit for said tube and connected between the control grid and the cathode thereof, a source of fluctuating uni-directional current having positive and negative terminals, a connection including a resistor from the anode of the tube to the positive terminal of the source, a second electronic tube provided with an anode, a cathode and an external control electrode, a connection from the anode side of said resistor to the control electrode of the second tube, cathode energizing circuits for both said tubes, means including series resistance for connecting both said energizing circuits in series across said source and a capacitive circuit effectively shunted across the terminals of the soure for lessening the amplitude of hum frequencies passing through the energizing circuit, said hum frequencies being poorly amplified in the tube due to said relationship existing in the first tube.

4. In radio receiving apparatus as described in claim 3 wherein the second tube is of the high vacuum type and means including a grounding circuit comprising a capacity between the negative terminal of said source and ground for providing a cathode grounding circuit.

5. In a system as described in claim 3 a connection including a resistor from the anode of the second tube to the positive terminal of said source, a third electronic device having anode, cathode and control electrodes, a connection from the control electrode of said third electronic device to the anode side of the last named resistor, said connection including a condenser, a connection from the control electrode of the third electronic tube to the negative terminal of said source, said connection including a resistor, a reproducing device connected in a connection from the anode of the third electronic tube tothe positive terminal of said source, energizing circuits for the cathodes of all three of the electronic tubes said energizing circuits being connected in series with a bias resistor across the source, said bias resistor being arranged so as to be both in the input and output circuits of the third electronic device whereby the drop across said bias resistor is utilized to bias the third electronic tube.

GNTHER JOBST. WALDEMAR WEHNERT. 

